Alloy for electrical contact-points



v ties, and will maintain smooth an contact surfaces." This is. accomplished'by UNITED STATES I JOSEPH 'A. wILnums,

OF CLEVELAND, OHIO.

ALZIhOY For. nnncrmcu. CONTACT-POINTS.

No Drawing. Application filed October 2 T0.all whom it may concern: 1

Be it known that I, J osnrn A. WILLIAMS, a citizenof the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Alloys for Electrical Contact-Points, of which the following is a specification.

This invention relates to' alloys, and more particularly to an' alloy for contact points for electrical apparatus.

The principal object of the invention is to provide an alloy for electrical "contact points', which possesses low resistance,

sparks but slightly, has good wearing qualiemploying abase metal of low electrical resistance, and treating this base metal in" a suitable manner to enable it to resist spark er'osion,ca used by electric action by increasing the cohesion of its particles. As the particles of the alloyhave becomemore compact, a smooth contactsurface may be obtained, and due to the cohesion of the particl'es, the alloy will wear away extremely slowly and remain smooth and bright.

,Heretofore, it has been the practice touse a metal'or' alloy for electrical contact points, which melts ata very high degree pfheat, the theory being that the continuous s arking produced heat, which had a'ten ency 1 to cause erosion or a wasting away of the -liaving a high melting point, but it is more essential for the substance to possess the contact points, and therefore the higher their melting paint, the longer in time would they wear. is invention has been developed on'a diiferenttheory, namely, that it was not necessary to use a metal or alloy clean Specification of Letters Patent. 4 Patented Nov. 16, 1920.

8,1918. Serial 110.25%935,

quality of great cohesion between its particles. On account of the great cohesion be tween the particles, the substance or alloy when used as electrical contactswould not flake off b electric action, and consequently there Won (1 be little wearin away and the contacts would remain smo'ot As low electrical resistance is very desirable in contact points, silver which ranks .high in this respect is employed for the base metal of the allo of the present invention. The silver is me ted by being heated in a crucible and a small quantity of lead is added thereto. The adding of-the lead gives the quality to the silver of resisting the dr erosion usually caused b electric action.

has been found that addi per cent. of lead to meltin silver produces the most satisfactor alloy for electrical contact points. This a 0y when used for electrical contacts, ossesses low resistance,

therefore the ten ency to become heated is reduced to a minimum, and as a consequence it does not oxidize but remain bright, and does not waste away. Furthermore, on account of the reat ductility and malleability of the alloy ue to intense cohesion between its particles, it ,does not waste away by flak ing of! in granules from spark erosion, but remains smooth.

Having fullydescribed my invention, ,what I claim is:

-1. An alloy forelectrical', contact points consisting of silver and a sufiicient quantity of 'lead' to increase the cohesion of its par.- ticles but less than one per cent. of lead.

1W1- of- 1 OSEPHIA.

2. An alloy consisting of silver 99%7 and.

ng one-half of one In testimon whereof-I aflixm signature. WIIZLIAMS. 

